About 11 genera,
170 species, North America to South America, Caribbean Islands, Africa, Asia to
Australia.

The Ehretiaceae
have been treated as one of five subfamilies of the Boraginaceae by many
botanists (Al-Shehbaz, 1991). Recent molecular work has suggested that the
traditionally recognized family Hydrophyllaceae is nested within this group
(Ferguson, 1998; Gottschling et al., 2001). One way of dealing with these data
is to expand the definition of Boraginaceae to include the Hydrophyllaceae, as
was advocated by the Angiosperm Phylogeny Group (1998, 2003), Judd et al.
(2002), and Craven (2005). Arguing against this interpretation is that it
creates a morphologically even more variable family that becomes accordingly
more difficult to circumscribe in floristic manuals. Also, although the
relationships among the subfamilies of Boraginaceae are still not fully
understood, it is clear that the individual subgroups mostly are amply distinct
based on both morphological and molecular data. Accordingly, Gottschling et al.
(2001) and Diane et al. (2002) have taken the opposite approach and suggested
the recognition of segregate families, with the Boraginaceae restricted to the
mostly temperate herbaceous genera formerly included in the subfamily
Boraginoideae. Although future research undoubtedly will result in further
refinements of classification within the Boraginaceae complex, it seems most
expedient in the present work to deviate from the system of Cronquist (1981,
1991) and to segregate the Ehretiaceae and Heliotropiaceae from the
Boraginaceae and Hydrophyllaceae.

The Ehretiaceae
are primarily a tropical and subtropical family of mostly shrubs and small
trees. The family generally differs from the Boraginaceae in its less strongly
lobed ovary with a more terminal, 2-branched style, fruits that often are
drupelike, and seeds with abundant endosperm, as well as several more esoteric
features. The sole Missouri representative is in a genus that is atypical for
some of these features.